title: Binding of 3'-methyl-N,N-dimethyl-4-aminoazobenzene metabolites to rat liver cytosol proteins and ligandin subunits.
abstract: Twenty min after i.p. administration of 3'-[14C]methyl-N,N-dimethyl-4-aminoazobenzene in corn oil to rats, 0.73% of administered radioactivity was present in the liver. Only 0.45% of radioactivity present in liver was recovered in the nuclear fraction, whereas 25% was present in the cytosol fraction. Twenty-seven % of cytosolic radioactivity was trichloroacetic acid precipitable, and 2% was immunoprecipitable with monospecific anti-rat liver ligandin immunoglobulin G. After 3 hr of administration, 3.2% of administered radioactivity was present in the liver, 40% of which was in the cytosol. Although 59% of radioactivity present in liver cytosol was trichloroacetic acid precipitable as compared to 27% at 20 min, the radioactivity precipitated by anti-ligandin immunoglobulin G was still 2%. When liver cytosol obtained from rats after 20 min of 3'-[14C]methyl-N,N-dimethyl-4-aminoazobenzene administration was fractionated on a Sephadex G-75 column, three peaks of radioactivity were observed. When cytosol was subjected to sodium dodecyl sulfate gel electrophoresis and fluorography, radioactivity was mainly associated with 5 proteins with molecular weights of 88,000, 47,000, 41,000, 31,000, and 22,000. When the immunoprecipitate obtained from cytosol with anti-ligandin immunoglobulin G was subjected to sodium dodecyl sulfate gel electrophoresis and fluorography, radioactivity was exclusively associated with the subunit of ligandin with a molecular weight of 22,000. Approximately 90% of the radioactivity in the immunoprecipitate was covalently associated with this subunit. These studies reveal that 3'-methyl-N,N-dimethyl-4-aminoazobenzene or its metabolites are selectively bound to the subunit of ligandin with a molecular weight of 22,000 and four other cytosol proteins in vivo.
mesh_terms: D000818:Animals; D003600:Cytosol / Q000032:analysis / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005982:Glutathione Transferase / Q000378:metabolism*; D007274:Injections, Intraperitoneal; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008113:Liver Neoplasms / Q000139:chemically induced; D008297:Male; D008749:Methyldimethylaminoazobenzene / Q000008:administration & dosage / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D013997:Time Factors; D004124:p-Dimethylaminoazobenzene / Q000031:analogs & derivatives*
chemical_list: D011506:Proteins; D008749:Methyldimethylaminoazobenzene; D004124:p-Dimethylaminoazobenzene; D005982:Glutathione Transferase